High-bandwidth memory (hereinafter referred to as “HBM”) is a type of the memory structure in which a plurality of semiconductor memory chips may be stacked on a memory buffer chip (or a register) which performs logic circuit functions. In this case, the buffer memory chips and the semiconductor memory chips may be connected to each other by through silicon vias (TSV).
A plurality of semiconductor memory chips (e.g., dies or devices) can be mounted on a printed circuit board (PCB) to implemented a memory module. The dual in-line memory module (DIMM) type memory module may be classified as a registered dual in-line memory module (RDIMM), a load reduced dual in-line memory module (LRDIMM), or FRDIMM.
Semiconductor memory devices which constitute the memory module may be divided into two or more ranks. That is, in the case of a dual-rank structure, a plurality of semiconductor memory devices on a substrate of a memory module are classified into two ranks, and semiconductor memory devices in the same rank may be accessed at the same time. As a result, a rank may mean a unit written or read together by a memory controller. Thus, for example, in the case that a single rank has a 64-bit data transfer width, dual ranks may have twice the data transfer width of the single rank, and quad ranks may have four times a data transfer width of the single rank.